Self-levelling motion detecting device and alarm system incorporating the same

ABSTRACT

A motion detecting device is adapted to be secured to a moveable object such as a door, window or curtain through which access to premises to be protected may be obtained. When the motion detecting device is moved, an electrical circuit is completed causing an alarm to be given. The motion detecting device includes a resilient spring finger that extends in cantilevered configuration from a support member in a direction other than vertically downwardly. Under the influence of gravity the spring finger assumes a curved configuration. An electrically conductive contact has an opening therein through which a part of the spring finger extends, the opening being of arcuate configuration with the curve of the opening in the contact member having its centre of curvature on the side of the opening that is closest to the means by which the motion detecting device may be secured to a moveable object.

United States Patent [191 Rempel et al.

m1 3,831,158 Aug. 20, 1974 SELF-LEVELLING MOTION DETECTING DEVICE AND ALARM SYSTEM INCORPORATING THE SAME [76] Inventors: Robert H. Rempel, Taylor Rd.,

Bracebridge; Joseph J. Bulger, 44 lronshield Crescent, Thomhill, Ontario, both of Canada [22] Filed: Apr. 30, 1973 [21] Appl. No.: 355,655

[52] US. Cl. 340/224, 340/52 H, 340/65, 340/262, 340/261, ZOO/61.45 R, ZOO/61.93

[51] Int. Cl G08c 17/00 [58] Field of Search 340/52 11, 65, 224, 262, 340/261; ZOO/61.45, 61.51, 61.93; 73/7l.2,

Primary Examiner-John W. Caldwell Assistant Examiner-Richard P. Lange Attorney, Agent, or FirmSim & McBurney [57] ABSTRACT A motion detecting device is adapted to be secured to a moveable object such as a door, window or curtain through which access to premises to be protected may be obtained. When the motion detecting device is moved, an electrical circuit is completed causing an alarm to be given. The motion detecting device includes a resilient spring finger that extends in cantilevered configuration froma support member in a direction other than vertically downwardly. Under the influence of gravity the spring finger assumes a curved configuration. An electrically conductive contact has an opening therein through which a part of the spring finger extends, the opening being of arcuate configuration with the curve of the opening in the contact member having its centre of curvature on the side of the opening that is closest to the means by which the motion detecting device may be secured to a moveable object.

10 Claims, 3 Drawing Figures SELF-LEVELLING MOTION DETECTING DEVICE AND ALARM SYSTEM INCORPORATING THE SAME This invention relates to a motion detecting device electric cells, interruption of any light beam by an intruder causing the giving of an alarm. Other systems use easily broken electrical conductors secured to the glass windows of premises to be protected, an alarm being given when a window is broken causing breakage of the conductors secured thereto and consequent interruption of an electrical circuit.

The instant invention is based on a different principle of operation than those previously described. More particularly, a unique motion detecting device is employed, this device being secured to some moveable object, such as a window, curtain or door, through which access to premises to be protected may be had. When the motion detecting device is moved, an electrical circuit is completed and an alarm sounded. A particular feature of the motion detecting device is that it need not be carefully installed, i.e., it can be hung offcentre or off-level to a certain extent without this misalignment resulting in immediate triggering of the alarm system. This is achieved by a particular arrangement and selection of components including a spring finger and an electrical contact, the former being cantilever supported and having a part thereof extending through an opening of arcuate configuration in the latter.

This invention will become more apparent from the following detailed description, taken in conjunction with the appended drawings, in which:

FIG. 1 is a perspective view of a motion detecting device and alarm signal generating system embodying this invention;

FIG. 2 is a side elevation showing aweighted spring finger that may be used in a motion detector embodying this invention; and

FIG. 3 is a block diagram of the motion detecting device and alarm signal generating system shown in FIG. 1.

Referring first to FIG. 3, there is shown a motion detecting device 10 embodying this invention, a tone generator 11, a modulator 12, an R.F. amplifier 13, an antenna 14 and a power supply which, in the embodiment shown in FIG. 3, is a battery.

Motion detecting device 10 is basically a switch and, when closed, connects battery 15 to each of tone generator ll, modulator l2 and RF. amplifier 13 to supply power thereto. Thus, when motion detecting device 10 is activated by movement thereof, tone generator 11 produces a tone signal which is modulated onto a suitable carrier wave by modulator 12. The modulated signal then is amplified by RF amplifier -13 andtransmitted via antenna 14.to a suitable receiver where the modulating signal is detected and activates an alarm, which may be an audible alarm, a visual alarm or any other alarm device. In any one premises to be protected at number of devices of the type shown in FIG. 3 may be employed each with a tone generator 11 that produces a different tone signal. The receiver then can be set up to detect and identify the different, tone signals LII so as to identify the particular device that has been activated and hence the ocation of unauthorized entry.

In a simple version of an alarm system embodying this invention components 11 to 14 may be dispensed with and a simple alarm provided that is activated directly by closure of the switch in motion detecting device 10.

The system shown in FIG. 3 is shown in greater detail in FIG. 1, to which reference now will be made. A housing 16 is provided and is divided into three compartments 17, 18 and 19. Compartment 17 houses battery 15. Compartment 18 houses motion detecting device 10. Compartment 19 houses tone generator 11, modulator 12, RF. amplifier l3 and antenna 14. One end wall 20 of housing 16 constitutes a door through which access may be had to battery compartment 17, while the front wall 21 of housing l6 is removeable to permit access to compartments l8 and 19. Secured to the top wall 22 of housing 16 are two tabs 23 and 24 with openings extending therethrough. Suitable fastening'devices may be passed through these openings in order to secure housing 16 to a moveable object such as a door, window or curtain.

Motion detecting device 10 consists of a resilient spring finger 25, an electrically conductive contact 26 and a spring finger support member 27. Support member 27 includes a block 28 of insulating material that is secured to and depends downwardly from the inner surface of top wall 22 of housing 16. Secured to block 28 is an electrical connector 29 that is connected via conductors (see FIG. 3) to tone generator 11, modulator l2 and RF. amplifier l3. Connector 29 also is electrically connected to spring finger 25, which is electrically conductive. Spring finger 25 extends in cantilevered configuration from support member 28. As housing 16 is intended to be mounted on the moveable object with its longitudinal axis generally horizontal, spring finger 25 also extends generally horizontally from support member 28, although it may extend more upwardly or downwardly from support member 28 than is shown in FIG. 1 if housing 16 is mounted such that its longitudinal axis is off the horizontal. In any event,

spring finger 25 extends from support member 28 in a direction other than vertically downwardly or vertically upwardly. As may be seen from FIG. 1, under the influence of gravity, the spring finger assumes a curved configuration of such a nature that the longitudinal curved axis of the spring finger is located above an imaginary straight line drawn through the free end of the spring finger and the point where the spring finger is engaged by support member 28. Located at the free end of spring finger 25 is a weight 30 which serves to accentuate motion of spring finger 25 in response to movement of housing 16.

Contact 26 is secured to and depends downwardly from the inner surface of top wall 22 of housing 16. It is electrically insulated from housing 16 by means of an insulating spacer 31. Contact 26 is electrically connected to one terminal of battery 15 (FIG. 3), the other terminal of the battery being connected to housing 16 itself. Each of components 11 to 13 inclusive also are connected to the housing which provides a return path to battery 15. Contact 26 includes a downwardly depending arm 32 having an opening 33 therein through which a part of spring finger 25 that is located between the free end thereof and the point where the spring finger is engaged by support member 28 extends. Opening 33 is arcuate in configuration with the curve of opening 33 having its centre of curvature on the side of the opening that is closest to tabs 23 and 24. It would be possible to have tabs 23 and 24 depend downwardly from the bottom wall of housing 16. In this event, the curvature of opening 33 would be opposite to that shown in FIG. 1.

Housing 16 is intended to be mounted on a moveable object such as a door or the like in such a manner that its longitudinal and transverse axes are horizontal. However, by virtue of the particular construction of motion detecting device 10, it is possible for housing 16 to be mounted so that its longitudinal or transverse axes are off the horizontal without causing a false activation of motion detecting device 10. More particularly, the arcuate configuration of opening 33 permits the transverse axis of housing 16 to be off the horizontal to a limited degree without there being engagement between contact 26 and spring finger 25. Similarly the longitudinal axis of housing 16 may be off the horizontal to a limited degree without causing contact between spring finger 25 and electrical contact 26. The extent to which the longitudinal axis may be off the horizontal without causing a false activation of motion detecting device is dependent upon the location of arm 32 relative to the free end of spring finger25. If arm 32 is located adjacent the free end of spring finger 25, the sensitivity of the motion detecting device will be high, but the degree of misalignment that it can tolerate will be low. On the other hand, if arm 32 is located adjacent support member 28, thesensitivity of the motion detecting device will be low, but the degree of misalignment that it can tolerate will be high.

In FIG. 2 there is shown a preferred embodiment of spring finger 25. It consists of a wire having a diameter of 0.018 inches and fabricated, for example, of phosphorbronze. It includes two helical coil sections 34 and 35 of 8 and 16 turns respectively and has an overall length of 2-3/ l6 inches. Coil 34 is 7/ 16 inches long, while coil 35 is /s inches long, and these two coils are separated by a length of wire of 5/16 inches. Extending from coil 34 is a length of wire of 3/ 16 inches, this extending /8 inches into a centrally located opening in weight 30. Extending from coil 35 is a length of wire of inches. Weight 30 is cylindrical in configuration having a diameter of 9/ l 6 inches and a depth of /1 inches. lts weight is approximately ounce. For a spring finger of this type slot 33 may be a segment having a radius of curvature of 1 Vi inch and a width of 1/16 inch. While spring finger shown in FlG. 2 is a preferred form of spring finger, those skilled in the art will appreciate that other types of spring fingers might be substituted therefore such as a simple straight wire of a resilient nature.

It will be understood from the foregoing that when housing 16 is mounted on a moveable object and that object remains still, there is no contact between spring finger 25 and arm 32 of electrical contact 26. However, when the object to which housing 16 is fastened is moved, spring finger 25 also moves relative to arm 32, this movement being accentuated and made more reliable by weight 30, making physical and electrical contact with contacts 26 and thus completing a circuit from battery 15 to tone generator 11, modulator 12 and RF. amplifier 13 whereby power is supplied to these components and'a tone signal modulated on a suitable carrier wave is transmitted by antenna 14.

While preferred embodiments of the invention have been disclosed herein, those skilled in the art will appreciate that changes and modifications may be made therein without departing from the spirit and scope of this invention as defined in the appended claims.

We claim:

1. A motion detecting device comprising a support member, a electrically conductive resilient spring finger having a free end, said spring finger extending in cantilevered configuration from said support member in a direction other than vertically downwardly or upwardly and thus under the influence of gravity assuming a curved configuration of such a nature that the longitudinal curved axis of said spring finger is located above an imaginary straight line drawn through said free end of said spring finger and the point where said spring finger is engaged by said support member, means adapted for securing said support member to a moveable object, and electrically conductive contact means positioned in fixed relationship to said support member and having an opening therein through which a part of said spring finger that is located between said free end thereof and the point where said spring finger is engaged by said support member extends, the opening in said contact means being of arcuate configuration with its centre of curvature above said part of said spring finger, the opening in said contact means being of sufficient size that said part of said spring finger can move to a limited extent therein without engaging said contact means, said contact means being adapted to be engaged by said spring finger in response to movement of said motion detecting device.

2. A motion detecting device according to claim 1 including a housing, said contact means, said support member and said means adapted for securing said support member to a moveable object all depending from said housing with said contact means, said support member and said spring finger being located within said housing.

3. A motion detecting system comprising the motion detecting device of claim 1, a power source and means connecting said power source in a circuit including said spring finger and said contact means for rendering said circuit conductive when said spring finger engages said contact means and for interrupting said circuit when said spring finger is disengaged from said contact means.

4. A motion detecting system according to claim 3 wherein said circuit includes alarm signal generating means.

5. A motion detecting system according to claim 4 wherein said alarm signal generating means includes a tone signal generator, a modulator for modulating said tone signal onto a carrier wave, an amplifier for amplifying the modulated carrier wave and an antenna for transmitting the latter signal.

6. A motion detecting device according to claim 1 including a weight mounted at said free end of said spring finger.

7. A motion detecting device according to claim 1 wherein said spring finger includes two spaced-apart helically wound coil sections, said part of said spring finger being a part thereof that is located between said coil sections.

8. A motion detecting device according to claim 7 including a weight mounted at said free end of said spring finger.

tion detecting device of claim 9, a power source and means connecting said power source in a circuit including said spring finger and said contact means for rendering said circuit conductive when said spring finger engages said contact means and for interrupting said circuit when said spring finger is disengaged from said contact means. 

1. A motion detecting device comprising a support member, a electrically conductive resilient spring finger having a free end, said spring finger extending in cantilevered configuration from said support member in a direction other than vertically downwardly or upwardly and thus under the influence of gravity assuming a curved configuration of such a nature that the longitudinal curved axis of said spring finger is located above an imaginary straight line drawn through said free end of said spring finger and the point where said spring finger is engaged by said support member, means adapted for securing said support member to a moveable object, and electrically conductive contact means positioned in fixed relationship to said support member and having an opening therein through which a part of said spring finger that is located between said free end thereof and the point where said spring finger is engaged by said support member extends, the opening in said contact means being of arcuate configuration with its centre of curvature above said part of said spring finger, the opening in said contact means being of sufficient size that said part of said spring finger can move to a limited extent therein without engaging said contact means, said contact means being adapted to be engaged by said spring finger in response to movement of said motion detecting device.
 2. A motion detecting device according to claim 1 including a housing, said contact means, said support member and said means adapted for securing said support member to a moveable object all depending from said housing with said contact means, said support member and said spring finger being located within said housing.
 3. A motion detecting system comprising the motion detecting device of claim 1, a power source and means connecting said power source in a circuit including said spring finger and said contact means for rendering said circuit conductive when said spring finger engages said contact means and for interrupting said circuit when said spring finger is disengaged from said contact means.
 4. A motion detecting system according to claim 3 wherein said circuit includes alarm signal generating means.
 5. A motion detecting system according to claim 4 wherein said alarm signal generating means includes a tone signal generator, a modulator for modulating said tone signal onto a carrier wave, an amplifier for amplifying the modulated carrier wave and an antenna for transmitting the latter signal.
 6. A motion detecting device according to claim 1 including a weight mounted at said free end of said spring finger.
 7. A motion detecting device according to claim 1 wherein said spring finger includes two spaced-apart helically wound coil sections, said part of said spring finger being a part thereof that is located between said coil sections.
 8. A motion detecting device according to claim 7 including a weight mounted at said free end of said spring finger.
 9. A motion detecting device according to claim 8 including a housing, said contact means, said support member and said means adapted for securing said support member to a moveable object all depending from said housing with said contact means, said support member and said spring finger being located within said housing.
 10. A motion detecting system comprising the motion detecting device of claim 9, a power source and means connecting said power source in a circuit including said spring finger and said contact means for rendering said circuit conductive when said spring finger engages said contact means and for interrupting said circuit when said spring finger is disengaged from said contact means. 